A new type of sensors obtained from the integration of graphene and CMOS

Graphene-quantum dots-CMOS-based sensor (Image courtesy ICFO/ D. Bartolome)
Graphene-quantum dots-CMOS-based sensor (Image courtesy ICFO/ D. Bartolome)

An article published in the journal “Nature Photonics” describes the development of the first graphene-based camera. A team of researchers from the Institute of Photonic Sciences (ICFO) integrated a CMOS-type circuit with graphene creating a high resolution image sensor consisting of hundreds of thousands of graphens-based photodetectors and quantum dots. The camera is sensitive to ultraviolet, visible and infrared light at the same time.

Graphene has been acclaimed for years as a revolutionary material in the field of electronics but its inclusion in devices is still problematic. In the case of digital cameras, the problem was to find the way to combine silicon semiconductors with CMOS (Complementary metal-oxide semiconductors), a type of technology used to design integrated circuits.

ICFO researchers found a solution to this problem that made it possible to create a camera with features superior to those based on silicon circuits due to its sensitivity to a wide range of wavelengths. The integration of graphene and CMOS will open the way for many optoelectronic applications such as low power optical data communications and the production of compact sensors with remarkable sensitivity.

The problem of graphene-CMOS integration was solved by taking colloidal quantum dots made of lead sulphide (PbS) and depositing them on graphene produced using the Chemical Vapor Deposition (CVD) technique and then depositing this hybrid system on a CMOS wafers with image sensor dies and the circuit specifically used for light detection.

Stijn Goossens, one of the authors of the research, pointed out that these sensors weres created using processes that are simple and cheap to be implemented without the need for complex material processing. These are processes at ambient temperature and conditions so don’t require any further processing that would increase costs. In essence, this is a kind of process that can be easily integrated on CMOS integrated circuits.

ICFO professor Frank Koppens also talked about the possibility to produce low-cost sensors for many other applications, for electronic devices such as smartphones but also for fire control systems and other security systems, and many more. Having overcome the obstacle of their production, it’s possible that the moment of graphene in this field has really arrived.

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